Pyrotechnic impact fuse

ABSTRACT

An explosive having cavities ( 16 ) is proposed for a pyrotechnic impact fuse ( 100 ) for high explosive shells ( 1 ). The sensitivity of the explosive lies in the class of secondary explosives, due to the cavities ( 16 ). Mechanical safety means can therefore be eliminated.

[0001] The invention concerns a pyrotechnic impact fuse as set forth in the classifying portion of claim 1.

[0002] A pyrotechnic percussion or impact fuse is known from DE 196 51 169 A1. Disposed in a ballistic cap of a high explosive shell on a so-called anvil is a secondary explosive 28 which is commercially available but which is made especially fireable or detonatable. That secondary explosive is not defined in greater detail.

[0003] There the object of the invention is to propose an explosive which explodes upon impact on a target.

[0004] That object is attained in accordance with claim 1.

[0005] Advantageous developments of the invention are set forth in the appendant claims.

[0006] In accordance with the invention, the impact detonating or firing means is a conventional explosive but with uniformly distributed, defined cavities. Due to those cavities of a diameter of from 0.2 -1.2 mm, the sensitivity of the explosive is below the sensitivity of tetryl. Tetryl is referred to as a secondary explosive and does not require any special mechanical safety means, as is required in the case of conventional explosive, fitted in fuses.

[0007] The cavities in the primary explosive are defined in a simple manner by glass balls, styropor balls, addition of polyurethane, the addition of gas in the casting or moulding procedure or by virtue of bores which are disposed transversely with respect to the main axis of the explosive body.

[0008] The invention is based on the operative principle that, upon impact of the projectile, shock wave initiation of explosive occurs due to imploding pores or cavities in the explosive mixture.

[0009] Embodiments of the invention are described hereinafter and illustrated in the drawing in which:

[0010]FIG. 1 is a view in longitudinal section of a high explosive shell, FIG. 2 is a phase illustration, and FIG. 3 is a simplified view of an explosive charge.

[0011] Referring to FIG. 1, a high explosive shell 1 comprises a casing 2 with a guide band 3, a base-screw 4, a main charge 5 of explosive and a cap 6.

[0012] The cap 6 and an anvil 7 are connected to a screw threaded ring 8 on the shell side.

[0013] The anvil 7 has a plurality of firing or detonation passages 10. They connect a space 11 at the cap side, to a conical recess 12 of the anvil 7.

[0014] The firing passages 10 are closed by foils 9 of metal such as aluminium.

[0015] A structured explosive 13, 15 of PETN, nitropenta, with cavities 16, is disposed in the space 11 and likewise the conical recess 12. A conventional explosive can also be arranged in the recess 12. The cavities 16 are defined by suitable bodies of styropor.

[0016]FIG. 2 shows the firing or detonation progression of the explosive 13 which is structured in accordance with the invention, upon on-target impact 17 of the shell 1.

[0017] A shockwave 20 which is shown by way of example produces firing or detonation potentials 21 in the phase 1 which is identified by reference 22, in the structured explosive 13, and causes partial firing 17 in the cavities 16, due to shockwave initiation.

[0018] In phase 2, see reference numeral 23, the fire sources 17.1 have expanded and form a detonation front 25 which extends in the space 11, see also FIG. 1.

[0019] When the detonation front 25 reaches the foils 9 at the firing passages 10, the procedure then involves firing through to the explosive charge 15 in the conical recess 12. That then causes detonation of the main charge 5 which breaks up the casing 2 into fragments (not shown).

[0020] As shown in FIG. 3, a test body 30 of PHX, plastic-bound explosive, has bores 32 which are disposed transversely with respect to its longitudinal axis 31. Conversion of the explosive into detonation energy occurs in the direction of the arrow 33. That takes place in the same manner as described with reference to FIG. 2.

[0021] All military explosives are suitable as the explosives. 

1. A pyrotechnic impact fuse (100) for high explosive shells and shells with an impact function with a pyrotechnic firing means (13) in a cap (6), and an explosive charge (5) for breaking up the shell (1), wherein the firing means (13) surrounds an anvil (7) at the shell side, characterised in that a mouldable or pressable explosive has uniformly distributed, defined cavities (16; 32) of a diameter of 0.2 to 1.2 mm.
 2. An impact fuse according to claim 1 characterised in that suitable explosives are HWC, hexogen, wax graphite, ocfol, octol, PHX, plastic-bound explosive, or PETN, nitropenta.
 3. An impact fuse according to claim 1 characterised in that the cavities (16) are defined by glass balls, styropor bodies, the addition of polyurethane, the supply of gas in the casting or moulding operation or by means of bores (32) which are disposed transversely with respect to the axis (31) of the explosive body (30). 